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Povzetek: The corrosion behaviour and environmental durability of injection- and compression-moulded Nd–Fe–B and Sm–Fe–N magnets were investigated. For injection-moulded magnets, the effects of magnetic powder type (Nd–Fe–B and Sm–Fe–N), magnetic powder particle size (100 µm and 400 µm), and polymer binder (PPS and PA12) on corrosion resistance were studied. For compression-moulded magnets with an epoxy binder, the effects of powder type and size were examined. Corrosion resistance was investigated using potentiodynamic polarisation in electrolytes of varying pH (1.8–12.8). The Sm–Fe–N magnets exhibited slightly better corrosion resistance than the Nd–Fe–B magnets, irrespective of the polymer binder. The finer magnetic powders (100 µm) showed lower corrosion resistance due to their larger specific surface area, with a more pronounced effect in the compression-moulded magnets. The type of polymer binder had only a minor effect. The hygrothermal corrosion resistance and thermal stability were evaluated using bulk corrosion (BCT) and thermal shock tests, respectively. Surface corrosion was observed in all magnets after the BCT, with the compression-moulded magnets exhibiting a greater irreversible loss of magnetic properties. The thermal shock test caused a temporary reduction in magnetic properties, with recovery after remagnetisation, demonstrating the good thermal stability of both magnet types.
Ključne besede: magnetic powder, injection moulding, compression moulding, polymer-bonded magnets, bulk-corrosion test, thermal shock test, polymer binders
Objavljeno v DiRROS: 04.05.2026; Ogledov: 123; Prenosov: 76
Celotno besedilo (23,16 MB)
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Povzetek: The thermal and viscoelastic performance of polymer blends is decisive for their deployment in advanced engineering and electronic applications. Here, we report a systematic investigation of immiscible poly(trimethylene terephthalate) (PTT)/polypropylene (PP) blends reinforced with multiwalled carbon nanotubes (MWCNTs). While the incorporation of MWCNTs did not markedly alter the thermal degradation profiles, it significantly modified the viscoelastic behavior by inducing a constrained polymer region within the PTT phase. Quantitative analysis of filler dispersion effectiveness, entanglement density, reinforcing efficiency, and constrained volume provides new insights into nanotube–matrix interactions. Rheological results revealed a terminal-to-nonterminal transition with increasing nanotube content, confirming percolated network formation at low filler loadings. These findings establish clear structure–property correlations that extend beyond qualitative descriptions, offering a predictive framework for tailoring immiscible blends through nanofiller engineering. Such insights highlight the potential of PTT/PP/MWCNT systems in functional applications, including lightweight structural components and conductive composites for electronics.
Ključne besede: polymer blends, thermal properties, viscoelastic properties
Objavljeno v DiRROS: 09.04.2026; Ogledov: 108; Prenosov: 88
Celotno besedilo (3,93 MB)
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Povzetek: Performance-based structural fire design relies on models that capture material and structural behaviour during heating and cooling. Such models require experimental data, but experiments are often time- and resource- intensive. Optimal Experimental Design (OED) can reduce the number of tests needed by minimizing the variance of parameter estimates. This study demonstrates the use of OED, using D-optimality as the optimization criterion, for an experimental setup that measures the thermal elongation of concrete specimens. In these tests, cylindrical concrete specimens are slowly heated to a predefined maximum temperature while their elongation is being measured. The goal of the experimental campaign is to calibrate a model for the free thermal strain of concrete during cooling. The OED determines the optimal exposure that is expected to result in the lowest variance around the mean values of the parameter estimates. The results of the OED are compared with a baseline experimental design without optimization, showing that the advantages of OED become increasingly evident as the number of experimental runs grows and intuitive reasoning becomes less reliable. In addition, the approach is validated considering real experimental data.
Ključne besede: optimal experimental design, concrete, thermal strain, cooling
Objavljeno v DiRROS: 08.04.2026; Ogledov: 130; Prenosov: 34
Celotno besedilo (1,10 MB)
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Povzetek: With the rise of performance-based structural fire design, understanding the behaviour of materials during both the heating and cooling phases of a fire has become essential. Traditionally, research has focused on the heating phase, resulting in limited data on material properties during cooling, in particular for the free thermal strain of concrete. This gap is critical, as free thermal strain significantly influences load redistribution in reinforced concrete structures. Two experimental campaigns were conducted to expand the available data: one using the UGent HIFREP (‘High Intensity Fast-Response Electric Radiant Panel’) and the other employing an electric furnace. The first test campaign provided an extensive dataset on the residual thermal strain, whereas the time- consuming furnace tests provided data for the entire fire event (heating and cooling). These datasets were used to update an existing model through Bayesian inference, coherently integrating the new information. The outcome is a comprehensive probabilistic model that accurately captures the free thermal strain behaviour of concrete throughout both heating and cooling, allowing for a full reliability-based evaluation of concrete structures in fire.
Ključne besede: concrete, cooling, free thermal strain, fire safety, structural fire engineering, experiments, bayesian inference
Objavljeno v DiRROS: 10.03.2026; Ogledov: 250; Prenosov: 47
Celotno besedilo (1,45 MB)
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Povzetek: The growing demand for lithium-ion battery transportation, coupled with inadequate regulatory frameworks, has led to frequent fire incidents during transit, resulting in substantial losses of life and property. These recurring accidents underscore the urgent need to enhance the safety of lithium-ion batteries throughout the transportation process. This review begins by identifying key factors affecting battery safety during transport, such as mechanical abuse, thermal abuse, air pressure variations, and salt concentration. It then synthesizes current technological advancements and real-world battery transportation scenarios to conduct a targeted analysis of the critical technical challenges constraining transportation safety limits—specifically, ventilation and heat dissipation strategies, thermal monitoring, and fire safety design—while systematically examining the limitations of existing research. Accordingly, the paper proposes actionable recommendations and technical measures to improve the safety of lithium-ion battery transportation. Additionally, it outlines existing international standards and testing protocols governing lithium-ion battery transport and highlights shortcomings in the current regulatory landscape. The insights presented herein could provide valuable guidance for optimizing safety protocols in the transportation of lithium-ion batteries.
Ključne besede: lithium-ion batteries, transportation safety, thermal runaway, fire safety
Objavljeno v DiRROS: 27.01.2026; Ogledov: 368; Prenosov: 234
Celotno besedilo (13,00 MB)
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